Vehicular instrument devices, which allow a vehicle driver to visually recognize information necessary to drive the vehicle by means of two instruments disposed in the instrument panel, are disclosed in Japanese Laid-Open Patent Publication No. 2000-168400 and Japanese Laid-Open Patent Publication No. 2002-67735.
Specifically, in the vehicular instrument device disclosed in Japanese Laid-Open Patent Publication No. 2000-168400, one of the instruments, which displays less urgent information such as information about parking lots, etc., is positioned in a substantially central area of the instrument panel, when the driver directs his or her line of sight toward the forward direction of the vehicle, and the other instrument, which displays more urgent information such as information about vehicle speed, route guidance for the vehicle and road traffic, is positioned in an area of the instrument panel that is closer to the steering wheel than the central area thereof.
In the vehicular instrument device disclosed in Japanese Laid-Open Patent Publication No. 2002-67735, one of the instruments, which displays more frequently viewed information such as information about vehicle speed and engine speed, is positioned in a substantially central area of the instrument panel, when the driver directs his or her line of sight toward the forward direction of the vehicle, and the other instrument, which displays less frequently viewed information such as information about brake malfunctions and battery charging failures, is positioned in an area of the instrument panel that is viewed inside the steering wheel.
Another vehicular instrument device disclosed in Japanese Laid-Open Patent Publication No. 2002-225592 has an instrument and a head-up display. The instrument displays information, the importance of which does not change even when the vehicle situation changes, such as information about vehicle speed and fuel level, which is positioned in a substantially central area of the instrument panel, or in an area of the instrument panel that is viewed inside the steering wheel when the driver directs his or her line of sight in the forward direction of the vehicle. The head-up display displays information of greater importance, such as warnings for preventing vehicle collisions, in an area of the front windshield near the instrument panel.
While the driver is driving the vehicle, the driver directs his or her line of sight through the front windshield toward an outside area in the forward direction of the vehicle. At this time, the driver's view covers a certain angular range around the line of sight, including the front windshield and a portion of the instrument panel.
With the vehicular display devices disclosed in the above publications, when the driver directs his or her line of sight in the forward direction of the vehicle, for example, the display area of the instrument that displays vehicle speed, which is important and viewed quite frequently by the driver, is viewed either (1) in a substantially central area of the instrument panel located outside of the steering wheel (Japanese Laid-Open Patent Publication No. 2000-168400, Japanese Laid-Open Patent Publication No. 2002-67735, and Japanese Laid-Open Patent Publication No. 2002-225592), or (2) in an area of the instrument panel located inside the steering wheel (Japanese Laid-Open Patent Publication No. 2002-225592).
In order to observe the displayed vehicle speed, the driver must move his or her head vertically and horizontally about the neck, in order to move the line of sight from the exterior area toward the display area of the instrument. If the display area of the instrument is viewed in a substantially central area of the instrument panel, then since the line of sight moves a greater distance horizontally than vertically, movement of the line of sight also requires a longer period of time when moving horizontally than when moving vertically. If the display area of the instrument is viewed in the area of the instrument panel inside the steering wheel, then the driver must move his or her line of sight by a large vertical distance.
Japanese Laid-Open Patent Publication No. 11-352943 and Japanese Laid-Open Patent Publication No. 2000-108722 disclose vehicular display devices having a first liquid crystal display unit, and a second liquid crystal display unit superposed on the first liquid crystal display unit. The first and second liquid crystal display units display information about vehicle speed, etc., for the driver to visually recognize.
In the vehicular display device disclosed in Japanese Laid-Open Patent Publication No. 11-352943, the first liquid crystal display unit displays vehicle speed, while the second liquid crystal display unit superposed on the first liquid crystal display unit displays vehicle speed in a superposed relation to the vehicle speed displayed by the first liquid crystal display unit. In the vehicular display device disclosed in Japanese Laid-Open Patent Publication No. 2000-108722, the first liquid crystal display unit displays route guidance information for the driver as well as the temperature outside of the vehicle, while the second liquid crystal display unit superposed on the first liquid crystal display unit forms a speedometer, comprising an arcuate array of display segments simulating an analog pointer, for displaying vehicle speed.
With the above vehicular display devices, various items of information required by the driver must be displayed by a plurality of display elements, which are disposed in the first liquid crystal display unit and the second liquid crystal display unit respectively.
The vehicular display devices of Japanese Laid-Open Patent Publication No. 11-352943 and Japanese Laid-Open Patent Publication No. 2000-108722 simultaneously display many items of information through the display elements. For allowing the driver to visually recognize such various items of information, the liquid crystal display units must be large in size and contain many display elements. As a result, each time the various items of information are displayed, the driver needs to move his or her line of sight in order to view the displayed information.